HECO said the negotiations are expected to result in contracts for approximately 260 MW of solar energy across the three islands, with each solar project connected to a four-hour battery storage system.

As the cost of renewable energy continues to fall, Hawaiian Electric, Maui Electric and Hawaii Electric Light say they already have more than 500 MW of renewable energy under contract — along with almost 80,000 private rooftop systems in operation.

Dive Insight:

Hawaii continues its urgent rush to abandon expensive oil-fired power plants in favor of renewables and storage, a sign the state's utilities are pressing the envelope of grid-edge resources and solar integration. If approved by Hawaii's Public Utilities Commission, HECO officials say the seven new projects will displace 1.2 million barrels of oil per year.

The large-scale solar and battery projects being proposed accelerate the utility's renewable energy drive "at some of the lowest prices we've seen to date," Shelee Kimura, HECO senior vice president of business development and strategic planning, said in a statement.

Hawaii generates almost two-thirds of its electricity from oil-fired plants, leaving it with the highest electricity rates in the United States, but is also attempting to transition to 100% renewables in less than 30 years.

In 2017, the state's renewable portfolio stood at less than 30%.

On Oahu, HECO is proposing three projects totaling 120 MW and 515 MWh of storage; on Maui, two projects will provide 75 MW and 300 MWh of storage; and on Hawaii Island, two projects would provide 60 MW and 240 MWh of storage.

The utilities say developers will begin community outreach activities in the coming weeks.

The growth of renewables is beginning to put downward pressure on electricity prices. Earlier this year, the PUC approved a 22-year power purchase agreement for utility Maui Electric from a solar-plus-storage system at approximately $0.18/kWh.